<template>
  <div>
    <a-row class="row" type="flex" justify="end">
      <a-col>
        <a-space align="end">
          <a-button
            class="left-button"
            size="small"
            :disabled="prevIsDisabled"
            @click="prevPage"
          ><a-icon
            type="left"
          /></a-button>
          <a-button class="page-button" size="small">{{ currentPage }}</a-button>
          <a-button
            class="right-button"
            size="small"
            :disabled="nextIsDisabled"
            @click="nextPage"
          ><a-icon
            type="right"
          /></a-button>
          <a-dropdown
            class="dropdown"
            size="small"
            placement="topCenter"
            :trigger="['click']"
            :disabled="dropdownIsDisabled"
          >
            <a-menu slot="overlay">
              <a-menu-item v-for="(size, index) in pageSizes" :key="index" @click="handleItemClick(size)">
                {{ `${size}${$t('itemsPerPage')}` }}
              </a-menu-item>
            </a-menu>
            <a-button size="small">{{ `${pageSize}${$t('itemsPerPage')}` }}<a-icon type="down" /> </a-button>
          </a-dropdown>
        </a-space>
      </a-col>
    </a-row>
  </div>
</template>

<script>
export default {
  name: 'Pager',
  props: {
    currentPage: {
      type: Number,
      required: true,
    },
    pageSize: {
      type: Number,
      required: true,
    },
    pageSizes: {
      type: Array,
      required: true,
    },
    total: {
      type: Number,
      required: true,
    },
    isLoading: {
      type: Boolean,
      required: false,
    },
  },
  data() {
    return {
      dropdownIsDisabled: false,
      prevIsDisabled: true,
    }
  },
  computed: {
    nextIsDisabled() {
      return this.isLoading || this.total < this.pageSize
    },
  },
  watch: {
    isLoading: {
      immediate: true,
      handler: function(val) {
        if (val) {
          this.dropdownIsDisabled = true
          this.prevIsDisabled = true
        } else {
          this.dropdownIsDisabled = false
          if (this.currentPage === 1) {
            this.prevIsDisabled = true
          } else {
            this.prevIsDisabled = false
          }
        }
      },
    },
    currentPage: {
      immediate: true,
      handler: function(val) {
        if (val === 1) {
          this.prevIsDisabled = true
        }
      },
    },
  },
  methods: {
    handleItemClick(size) {
      this.$emit('showSizeChange', size)
    },
    nextPage() {
      const pageNum = this.currentPage + 1
      this.$emit('change', pageNum)
    },
    prevPage() {
      const pageNum = this.currentPage - 1
      this.$emit('change', pageNum)
    },
  },
}
</script>

<style lang="less" scoped>
.row {
  margin-top: 5px;
  .left-button {
    padding: 0;
    width: 24px;
  }
  .right-button {
    padding: 0;
    width: 24px;
  }
  .page-button {
    padding: 0;
    width: 24px;
  }
}
</style>
